Vacuum cleaner

ABSTRACT

A multi-speed electrically driven, lightweight vacuum cleaner with a switch manually held closed for momentary extra high speed and air volume surge. A warning light responsive to rising temperature of motor cooled by filtered exhaust air passing through the motor indicates when a filter bag should be emptied.

United States Patent 1 3,695,006

Valbona et al. 1 51 Oct. 3, 1972 [54] VACUUM CLEANER References C t d 72Inventors: Bruno M. Valbona, Avon; William UNITED STATES PATENTS i a" gg 2,789,660 4/1957 Brown ..15/319 x 3,232,030 2/1966 Owenmark ..55/217[73] Assignee: Dynamics Corporation of America, 3,319,282 5/1967MacFarland ..l5/3l9 New York, NY. Primary Examiner-Dennis E. Talbert,Jr. [22] Flled' Oct. 1970 Attorney-Harbaugh and Thomas [21] Appl. No.:83,504

[57] ABSTRACT [52] US. Cl. ..55/274, 15/319, 15/344, A multi speedelectrically driven, lightweight vacuum 15/347 15/412 55/357 55/36155/467 cleaner with a switch manually held closed for mo- SS/DIG' 3mentary extra high speed and air volume surge. A cL n u ni ..B0ld respos e to temperature of [58.] new of 1 motor cooled by filtered exhaustair passing through 3 339, 412, 344:, the motor indicates when a filterbag should be emptied.

19 Claims, 12 Drawing Figures VACUUM CLEANER CROSS REFERENCE OF RELATEDAPPLICATION Valbona et al., filed of even date Oct. 23, 1970, Ser. No.83,300 for Lightweight Vacuum Cleaner.

BACKGROUND OF INVENTION In the general field and use of a householdvacuum cleaner for floor coverings, two speeds, HI and LO, generallyprovide results satisfactory to a housewife, but very often conditionsarise where something is on the floor that requires extra time andattention for its removal, such as threads, tiny pieces of tape andpaper, animal hair, small pebbles, etc., which heretofore require extraand burdensome manipulation of the pickup nozzle and generally alongwith it the manual lifting of the vacuum cleaner body itself. This isparticularly the situation where the vacuum cleaner is a hand supportedunit. Under these special conditions a surge of volume air flow, alsoincreases vacuuming conditions at the nozzle and saves time and userfatigue.

Another problem that repeatedly occurs is the inattentiveness of theuser regarding the emptying of the filter bag as often as it should beemptied to maintain a proper efficiency for both HI and LO speeds thatis desired for optimum operating conditions.

SUMMARY OF THE INVENTION These problems are met by an extra surge ofairflow and vacuum when desired and by a signal indicating when a filterbag should be emptied. It is found that both of these cooperate for theuser to maintain the proper efficiency of the vacuum cleaner at allspeeds.

The present invention relates to providing and maintaining the speed andefficiency of a vacuum cleaner in which a hand set switch for the motorselects an airflow and vacuum volume speed within a speed range that avacuum cleaner will be operated during sustained use, and a normallyopen hand switch, momentarily held closed, is provided to override thehand set switch for momentary extra performance results at an increasedairflow volume and vacuum surge speed. An automatic switch not onlyindicates the existence of a clogged or filled condition of the filterbag that diminishes its potential efficiency for the sustainedoperation, but if potential motor temperature may be different fro HIand surge speeds it also indicates if the momentary extra performance isbeing resorted to more often than would be expected as when the bagshould be emptied more often for surge operation. Overuse of the surgespeed thereby indirectly indicates when a bag should be emptied for thatpurpose. Therefore, by the unconscious reaction of the user resulting inan overuse of the surge button, the user appreciates the situation andrestores normal efficiency of the vacuum cleaner by emptying the bag.This reduces the need for excess surge use. The end result is a betteroverall efficiency, less manipulation fatigue and a saving in cleaningtime. This warning is provided by a simple warning light responding tothe heat of the blower motor that is located where it is, preferablycooled by the exhaust filtered air going through it. The less airpassing through the filter bag due to retardation, the less air there isto cool the motor. This results in a greater accumulation of heat in themotor stator, and a higher temperature 5 desired, if there is delay inemptying the bag.

The speed control in the present invention is accomplished in severalways usable with several types of motor circuits, namely, motors havinga plurality of single or cowound field coils on the stator poles whichare of the same or different impedances; field coils connected in seriesor in parallel, or permutations of both; or, the electrical powerpotential is changed by a rectifier or resistance.

It is preferred that all field coils share energization of the motor atall speeds and both stator poles are energized at each speed to assuretemperature increase.

Another object of the invention is to utilize a separate power surgeswitch that has to be manually held while it is closed so that it is notinadvertently or easily left on.

A further object is to provide an airflow vacuum surge speed that isattained without changing the manually set operating speed, either HI 0rLO, at which the vacuum cleaner was or will be operating when the surgeis turned on or off, respectively.

Another object of the invention is to provide a lightweight vacuumcleaner that is weight-supported essentially by its nozzle on the floorat the lower end for full weight agitation of the nap of carpeting,supported manually at the other end by the user, and is controlled toeffectively reduce the need for repeated passes of the nozzle overparticular areas of the carpeting whereby fatigue is reduced whileimproving performance and saving time in a cleaning operation.

Other and further objects and advantages will appear from thedescription and claims which follow.

IN THE DRAWING FIG. 1 is a side elevational, partially cut away view ofa lightweight, manually supported vacuum cleaner embodying theinvention;

FIG. 2 is a top plan view of a portion of the handle showing thelocation of the switches and indicator light;

FIG. 2A is a side elevational cut away view showing the intimate contactof a signal lightthermostat with the outer surface of the motor statoras shielded from surrounding air in the motor compartment;

FIG. 3 is a diagrammatical view of a motor control circuit as controlledby a slide switch and push button switch for a two pole universal motorstator having four distinct permutatable field coils;

FIGS. 3A and 3B along with FIG. 3 indicate the three switches positionsfor OFF, L0 and HI;

FIG. 4 indicates the coil permutations involved with the three positionswitch and the surge speed;

FIG. 5 is a diagrammatical view of a single wound coil on each statorpole utilizing a rectifier with the armature electrically connected atone side of the field;

FIG. 5A indicates the coil permutations for a surge for each HI and LOspeeds;

FIGS. 6 and 6A are views similar to FIGS. 5 and 5A showing thepermutations of four coils in which all connections are seriesconnections with a diode in one permutation circuit of the field coils;

FIG. 7 shows a circuit like that shown in FIG. 6 with the diode inanother permutation circuit of the field coils wherein three speedchoices are available merely by changing location of one of the switchrelations and diode can be used with either one of two of the speeds andthe motor armature is located electrically to one side of the fieldcoils.

DESCRIPTION OF PREFERRED EMBODIMENTS In FIG. 1 is illustrated alightweight portable vacuum cleaner having an elongated body 10 with acarrying handle 12 on the main housing 15, a floor engaging nozzle 14supported on a tube 16 adjustably telescoping into the body at the lowerend, and a removable motor or upper housing 18 at the other end. Theupper housing 18 has a working handle 20 that curves downwardly forcomfortable use and is provided with a narrow neck portion 22 which canbe gripped by hand as a secondary handle, which terminates in anenlarged portion 24 having a closed opening 26 therethrough to receivethe fingers of a users hand to serve as a primary handle 28 by which thebody and nozzle can be manually moved easily back and forth over a floorcovering by the users fingers engaging either end of the handle opening26. g

In front of the primary handle 28 and above the secondary handle 22 arethe buttons of a main switch 30, a spring return push button or slidebutton for the surge" switch S, and the bezel of a reminder red light 32controlled by a thermal responsive switch 34 (FIG. 2A). The main housingcomprises a vacuum compartment 36 which loosely receives a filter bag 40therein having porous stiff walls. The opening at the lower end of thefilter bag closed by a plate 42 having an opening receiving the upperend 16A of the tube 16 therethrough opening into the bag. Air filteredthrough the wall of the filter bag moves longitudinally through theflutes defined by the ribs 38 to the open end of the compartment 36which is closed by the removable upper housing 18 held by trunk snapfasteners 44 which provide for emptying or renewing the bag 40. Themotor 46 is mounted in the upper housing and drives a blower 48 whichdraws air from the compartment 36, and as constrained by a baffle 38forces the air through the open space within the motor housing andaround the stator poles of the motor and ejects it through a grille 49as indicated by the air flow arrows in FIG. 1.

The thermally responsive switch 34 is preferably a single pole signalthrow switch mounted on the side of the motor, preferably in directcontact with the field core, and shielded from motor compartment air bya shield 50 so that the bimetal blade thereof is influenced almostentirely by the temperature of the motor housing 49 where it is indirect heat exchange contact with the stator core 52 of the motor.

Referring to the motor circuit diagrams of the respective FIGS., thecircuits illustrated are self explanatory except possibly in FIG. 5where the coils C and D are shown electrically connected in series atone side of the armature. They are physically on separate poles of thestator and the armature E is physically between them. Otherwise, thecoils are physically associated the same as they are shown circuitwise.

The switch numbers 1, 2, 3, 4, 5, 6 and 7 in the diagrams are disposedbetween the two switch contacts that are closed by the respectivemovable switch conductors. The field coils that are wound on the statorpoles are indicated by letters A, B, C and D and are designed and ofimpedances which provide at least the HI and LO speeds of conventionalvacuum cleaners in the several embodiments. In the chart FIGS. 3A, 5Aand 7 the permutations of the coils are set forth to represent a seriesconnection (FIG. 4) such as AB, and a parallel configuration as by A/B.The switches l, 2 and 3 that are shown closed as by 2 for series coilsAB and switches 13 for A/B where the coils are connected in parallel(FIG. 4). See switches 4, 5 and 6 similarly arranged (FIGS. 3A and 5A).

As diagrammatically shown in FIG. 3 the air volume surge switch S is acombination of a single pole single throw for switch 2 and a double polesingle throw switch for switches 1 and 3 in which slidable bridgingconductors 1A and 3A are in continuous contact with the respective upperterminals of switches l and 3 and when carried downwardly by thedielectric plunger S1 as manually actuated by push button S2 theterminals of switch 2 are closed. The plunger movement first moves thebridging conductor 2C away from and opens the terminals of switch 2.Then, secondly the conductors 1A and 3A bridges and close Switches 1 and3 respectively which involve the terminals of switch 2 separately.

A spring SS urges the plunger S1 to its original position shown in FIG.3 and the manually induced action is to move the switch manually from aposition connecting coils in series AB by switch 2 where the coilimpedances are additive for lesser wattage to a parallel configurationA/B by switches l and 3 where the composite coil impedance is reducedand provide greater wattage for the increased blower load that occurs athigher speeds.

The same operational effect is provided to vary the impedance andresulting wattage for coils C and D by a three position switch 30 whichcomprises a double pole double throw slide switch having slidingconductors 30A and 303 whose switch contacts 4 and 6 are open whenswitch 5 contacts are closed to connect coils C and D in series CD (FIG.3B). Switch 5 contacts are opened when switches 4 and 6 contacts areclosed to connect coils C and D in parallel C/D (FIG. 5A) when the slidebutton 30S is manually actuated to the position illustrated.

With these two switches there are four permutations with four coils asshown in FIG. 4, plus the OFF position shown in FIG. 3. The switches Sand 30 can be interchangeably used and also the impedances of the coilsin FIG. 3 can be different and designed to provide optimum results inthe respective permutations. By way of example, with an inside openingof 1.250 inches in diameter for the conduit 16 and with a filter bag inplace and the nozzle 14 wide open, the motor, blower and circuitry aredesigned to rate 15,000 R.P.M. at surge speed, 13,000 R.P.M. at HI and10,000 R.P.M. at LO speeds.

In FIGS. 5 and 6 a rectifier R is employed in the motor circuits for theLO speed settings. These are connected in series with the motor andshunted by a single pole, single throw switch SR whose conductor 26C isnormally held open by spring SS. Whenever the switch SR is closed thecurrent applied to the motor is changed from half wave rectified currentto full wave A.C. current to provide higher wattage and thereby higherspeeds.

In FIGS. 5 and 6 there is a surge speed for both HI and LO set speedoperations since the rectifier is controlled by a separate switch SR andalthough represented as a push-pull with a center OFF it, along withswitch 30A of FIG. 6, can be a standard single pole-double throw switch.Switch 30A is urged by spring SS to a REG position while switch SR has acenter OFF position.

In FIG. 6 the surge speed switch 30 is related to switching the coilpermutations from ABCD (switch 1 indicated by Reg) Reg to BD (switch 2).With switch 30A in Reg position the SR switch controls HI and LOoperations with coils ABCD in series.

Referring to FIG. 7, although the parallel connected switch SR andrectifier R can be connected as a unit in series with coil B in theconnection Z between and the common pole CP of switch 1 and 2 wouldprovide an embodiment in which the surge switch 30 can only be effectiveif the vacuum cleaner is in HI or L operation, it is preferred toconnect the switch SR and switch 30 as units in series with coil Ainstead of coil B through the connection Y between the other pole ofswitch 1 and coil A as shown in FIG. 7. Then the surge switch 30 byswitches 2 and 3 and coils BC supersedes any operation of the OFF, LO,l-II switch SR. In both instances, however, of FIGS. 6 and 7 the SRswitch unit serves as a speed selector and switch 30 operates as thespring return surge switch. This is a modification of the otherembodiments where the speed selector switch 30 is supplied with thespring SS to serve as the surge switch which normally connects coils Aand B and coils C and D in series through switches 2 and 3,respectively. Thus, in these embodiments, a closing of the switch 2(FIG. 6) of switch 30A or switches 2 and 3 of switch 30 at any timeenergizes coils BC at surge speed including the condition when thevacuum cleaner is not otherwise energized.

Having thus described the invention and various embodiments thereof itwill be appreciated how the stated objects and advantages are attained,and how various and further modifications can be made includingcombining both switches in housing for single installation purposes orsingle button control.

What is claimed is: l. A portable electrically powered vacuum cleanerfor household use having a variable speed motorblower with a statorutilizing a plurality of field coils, an accessible compartment for afilter bag and means for conducting the flow of air through a filter bagin the compartment, the combination of means for conducting flow of airfrom the filter bag in the compartment through the motor to cool thestator of the motor,

manually settable switch means connected to said field coils for varyingthe speed of the motorblower to control the volume flow of air throughsaid bag and motor stator within a range of working speeds,

manually held switch means including a switch and impedance varyingmotor circuit connections to increase the wattage of electrical currentthrough said motor to surge the volume flow of air through said bag andmotor stator at a speed higher than said range of speeds, and

means responsive to the temperature of said stator core for indicatingcritical changes of permeability of said bag to air flow therethroughfor all speeds respectively.

2. The vacuum cleaner defined in claim 1 in which said settable switchmeans includes a half wave electrical current rectifier and saidmanually held switch means includes a switch shunting said rectifier.

3. The vacuum cleaner defined in claim 1 in which said manually heldswitch means includes permutable switches changing motor-blower fieldcoil connections between series and parallel configurations to changetheir composite impedance.

4. The vacuum cleaner defined in claim 1 in which said settable switchmeans includes permutation switches selectively connecting in serieswith each other two separately operative circuits of series connectedpairs of field coils to provide a high impedance field, one of theseries circuits including a half wave rectifier shunted by a switchcontrolled by one of said switch means.

5. The vacuum cleaner defined in claim 4 in which said one of saidswitch means is the settable switch means.

6. The vacuum cleaner defined in claim 1 including resilient meansurging said manually held switch means to a resting position in whichthe impedance controlled thereby is the highest.

7. An electrically powered portable vacuum cleaner for household usehaving an accessible compartment for a filter bag and means forconducting the flow of air through a filter bag in the compartment andincluding 1. a variable speed motor-blower whose field core includes aplurality of stator poles and a plurality of field coils thereon and anarmature driving a blower to force air through said filter bag,

2. manually operated switch means including a. an electrical connectionincluding a first switch to connect two field coils in serieselectrically to provide a high impedance field on the field core for alow speed performance,

b. an electrical connection including a second switch shunting one coiland said first switch,

. an electrical connection including a third switch shunting the othercoil and said first switch, said second and third switches connectingthe coils in parallel to provide a low impedance field on the field corein series with the armature for high speed performance,

3. an electrical current flow reducing means in series with the armatureand said two field coils,

4. manually operated switch means controlling the current flow reducingmeans and movable alternately to two positions in one of which a lowimpedance is presented to the current flow for a high speed performanceand the other position a high impedance is presented to the current flowin the circuit for low speed performance, and

5. resilient means urging one of said switch means to a resting positionof high impedance and manually movable in coaction with the other switchmeans to provide a composite low impedance speed surge flow of airthrough said filter bag.

8. The vacuum cleaner defined in claim 7 in which said current flowreducing means includes a half wave rectifier and said switch meanscontrolling the current flow shunts the rectifier in its low impedanceposition.

9. The vacuum cleaner defined in claim 8 in which said resilient meansactuates the half wave rectifier switch means.

10. The vacuum cleaner defined in claim 7 in which said resilient meansurges the first mentioned switch means to its high impedance position.

11. The vacuum cleaner defined in claim 7 in which said flow reducingmeans is a second pair of field coils inductively coupled with saidstator core and connected in series with the armature, and

said switch means controlling said flow reducing means including afourth switch connection to connect the second pair of field coils inseries, a fifth switch connection to shunt one of the second pair ofcoils and said fourth switch, and a sixth switch connection to shunt theother of the second pair of coils an said fourth switch, said fifth andsixth switches connecting the second pair of coils in parallel andopening said fourth switch to provide a low field impedance. 12. Anelectrically powered portable vacuum cleaner for household use having anaccessible compartment for a filter bag and means for conducting theflow of air through a filter bag in the compartment and including avariable speed motor-blower whose field core includes a plurality ofstator poles and a plurality of field coils thereon connected in seriescircuit with an armature between two power connections to drive a blowerand force air through said filter bag,

an electrical connection including a first switch to connect two of saidfield coils electrically in series,

an electrical connection including a second switch to connect two otherfield coils in series and in series with the armature,

an electrical current flow reducing means in series with one of saidelectrical connections,

manually operated switch means controlling the current flow reducingmeans and being movable alternately between two positions in one ofwhich a low impedance is presented to the flow of current in said one ofthe connections and the other of which a high impedance is presented tothe flow of current in the circuit,

an electrical connection including a third switch to connect one of saidtwo field coils in series with one of the power connections, anelectrical connection including a fourth switch to connect the other ofsaid two field coils in series with the other one of said powerconnections,

manual means for alternately closing said first and second switches as aunit and said third and fourth switches as a unit,

means urging the last said manual means to close the switches in theconnections having said flow reducing means in series therewith.

13.The vacuum cleaner defined in claim 12 in which said four switchesconstitute a double pole double throw type switch.

14. The vacuum cleaner defined in claim 12 in which the first mentionedswitch is a double pole single throw switch with an OFF position.

15. The vacuum cleaner defined in claim 12 including a rectifierconnected in series in said series circuit,

switch means connected in said series circuit in parallel with saidrectifier, and

manual means for actuating the last mentioned switch means.

16. The vacuum cleaner defined in claim 15 in which the said two fieldcoils are connected at one end to the armature, and

said two other field coils are connected in series with said rectifier.

17. An electrically powered portable vacuum cleaner for household usehaving an accessible compartment for a filter bag and means forconducting the flow of air through a filler bag in the compartment andincluding a variable speed motor-blower whose field core includes aplurality of stator poles and a plurality of field coils thereoncollectively connected in series circuit with an armature between twopower connections to drive the motor blower and force air through saidfilter bag,

an electrical connection connecting two of said field coils electricallyin series as a unit,

an electrical connection connecting two other field coils in series as aunit an electrical connection including first switch means to connectsaid units in series with each other in said series circuit,

an electrical connection including second switch means to connect one ofsaid units to shunt the other unit in said series circuit,

manual means for alternately opening and closing said switch unitsoppositely and simultaneously,

means urging the last said manual means to close the first switch andopen said second switch.

18. An electrically powered appliance for household use and including avariable speed motor and a blower driven thereby for cooling said motor,

said motor having an armature and a field core including a plurality ofstator poles and a plurality of field coils thereon, said field coilsbeing collectively connected in series circuit at one end with saidarmature,

a first connection connecting said armature to one side of a source ofelectrical current and said coils to drive said motor, said armaturebeing mechanically located between said field coils and said one side ofsaid source of electrical current,

an electrical connection connecting two of said field coils on oppositestator poles electrically in series as a unit,

another electrical connection connecting two other of said field coilson opposite stator poles electrically in series as a unit,

a third electrical connection including a first switch means to connectsaid coil units in series with each other in said series circuit,

a fourth electrical connection connecting the other end of said seriescircuit to the other side of a source of electrical current andincluding a second switch means to connect one of said coil units toshunt the other unit in said series circuit to said second source ofelectrical current,

manual means for alternately opening and closing said switch meansoppositely and simultaneously,

1. A portable electrically powered vacuum cleaner for household usehaving a variable speed motor-blower with a stator utilizing a pluralityof field coils, an accessible compartment for a filter bag and means forconducting the flow of air through a filter bag in the compartment, thecombination of means for conducting flow of air from the filter bag inthe compartment through the motor to cool the stator of the motor,manually settable switch means connected to said field coils for varyingthe speed of the motor-blower to control the volume flow of air throughsaid bag and motor stator within a range of working speeds, manuallyheld switch means including a switch and impedance varying motor circuitconnections to increase the wattage of electrical current through saidmotor to surge the volume flow of air through said bag and motor statorat a speed higher than said range of speeds, and means responsive to thetemperature of said stator core for indicating critical changes ofpermeability of said bag to air flow therethrough for all speedsrespectively.
 2. The vacuum cleaner defined in claim 1 in which saidsettable switch means includes a half wave electrical current rectifierand said manually held switch means includes a switch shunting saidrectifier.
 2. manually operated switch means including a. an electricalconnection including a first switch to connect two field coils in serieselectrically to provide a high impedance field on the field core for alow speed performance, b. an electrical connection including a secondswitch shunting one coil and said first switch, c. an electricalconnection including a third switch shunting the other coil and saidfirst switch, said second and third switches connecting the coils inparallel to provide a low impedance field on the field core in serieswith the armature for high speed performance,
 3. an electrical currentflow reducing means in series with the armature and said two fieldcoils,
 3. The vacuum cleaner defined in claim 1 in which said manuallyheld switch means includes permutable switches changing motor-blowerfield coil connections between series and parallel configurations tochange their composite impedance.
 4. The vacuum cleaner defined in claim1 in which said settable switch means includes permutation switchesselectively connecting in series with each other two separatelyoperative circuits of series connected pairs of field coils to provide ahigh impedance field, one of the series circuits including a half waverectifier shunted by a switch controlled by one of said switch means. 4.manually operatEd switch means controlling the current flow reducingmeans and movable alternately to two positions in one of which a lowimpedance is presented to the current flow for a high speed performanceand the other position a high impedance is presented to the current flowin the circuit for low speed performance, and
 5. resilient means urgingone of said switch means to a resting position of high impedance andmanually movable in coaction with the other switch means to provide acomposite low impedance speed surge flow of air through said filter bag.5. The vacuum cleaner defined in claim 4 in which said one of saidswitch means is the settable switch means.
 6. The vacuum cleaner definedin claim 1 including resilient means urging said manually held switchmeans to a resting position in which the impedance controlled thereby isthe highest.
 7. An electrically powered portable vacuum cleaner forhousehold use having an accessible compartment for a filter bag andmeans for conducting the flow of air through a filter bag in thecompartment and including
 8. The vacuum cleaner defined in claim 7 inwhich said current flow reducing means includes a half wave rectifierand said switch means controlling the current flow shunts the rectifierin its low impedance position.
 9. The vacuum cleaner defined in claim 8in which said resilient means actuates the half wave rectifier switchmeans.
 10. The vacuum cleaner defined in claim 7 in which said resilientmeans urges the first mentioned switch means to its high impedanceposition.
 11. The vacuum cleaner defined in claim 7 in which said flowreducing means is a second pair of field coils inductively coupled withsaid stator core and connected in series with the armature, and saidswitch means controlling said flow reducing means including a fourthswitch connection to connect the second pair of field coils in series, afifth switch connection to shunt one of the second pair of coils andsaid fourth switch, and a sixth switch connection to shunt the other ofthe second pair of coils an said fourth switch, said fifth and sixthswitches connecting the second pair of coils in parallel and openingsaid fourth switch to provide a low field impedance.
 12. An electricallypowered portable vacuum cleaner for household use having an accessiblecompartment for a filter bag and means for conducting the flow of airthrough a filter bag in the compartment and including a variable speedmotor-blower whose field core includes a plurality of stator poles and aplurality of field coils thereon connected in series circuit with anarmature between two power connections to drive a blower and force airthrough said filter bag, an electrical connection including a firstswitch to connect two of said field coils electrically in series, anelectrical connection including a second switch to connect two otherfield coils in series and in series with the armature, an electricalcurrent flow reducing means in series with one of said electricalconnections, manually operated switch means controlling the current flowreducing means and being movable alternately between two positions inone of which a low impedance is presented to the flow of current in saidone of the connections and the other of which a high impedance ispresented to the flow of current in the circuit, an electricalconnection including a third switch to connect one of said two fieldcoils in series with one of the power connections, an electricalconnection including a fourth switch to connect the other of said twofield coils in series with the other one of said power connections,manual means for alternately closing said first and second switches as aunit and said third and fourth switches as a unit, means urging the lastsaid manual means to close the switches in the connections having saidflow reducing means in series therewith.
 13. The vacuum cleaner definedin claim 12 in which said four switches constitute a double pole doublethrow type switch.
 14. The vacuum cleaner defined in claim 12 in whichthe first mentioned switch is a double pole single throw switch with anOFF position.
 15. The vacuum cleaner defined in claim 12 including arectifier connected in series in said series circuit, switch meansconnected in said series circuit in parallel with said rectifier, andmanual means for actuating the last mentioned switch means.
 16. Thevacuum cleaner defined in claim 15 in which the said twO field coils areconnected at one end to the armature, and said two other field coils areconnected in series with said rectifier.
 17. An electrically poweredportable vacuum cleaner for household use having an accessiblecompartment for a filter bag and means for conducting the flow of airthrough a filler bag in the compartment and including a variable speedmotor-blower whose field core includes a plurality of stator poles and aplurality of field coils thereon collectively connected in seriescircuit with an armature between two power connections to drive themotor blower and force air through said filter bag, an electricalconnection connecting two of said field coils electrically in series asa unit, an electrical connection connecting two other field coils inseries as a unit an electrical connection including first switch meansto connect said units in series with each other in said series circuit,an electrical connection including second switch means to connect one ofsaid units to shunt the other unit in said series circuit, manual meansfor alternately opening and closing said switch units oppositely andsimultaneously, means urging the last said manual means to close thefirst switch and open said second switch.
 18. An electrically poweredappliance for household use and including a variable speed motor and ablower driven thereby for cooling said motor, said motor having anarmature and a field core including a plurality of stator poles and aplurality of field coils thereon, said field coils being collectivelyconnected in series circuit at one end with said armature, a firstconnection connecting said armature to one side of a source ofelectrical current and said coils to drive said motor, said armaturebeing mechanically located between said field coils and said one side ofsaid source of electrical current, an electrical connection connectingtwo of said field coils on opposite stator poles electrically in seriesas a unit, another electrical connection connecting two other of saidfield coils on opposite stator poles electrically in series as a unit, athird electrical connection including a first switch means to connectsaid coil units in series with each other in said series circuit, afourth electrical connection connecting the other end of said seriescircuit to the other side of a source of electrical current andincluding a second switch means to connect one of said coil units toshunt the other unit in said series circuit to said second source ofelectrical current, manual means for alternately opening and closingsaid switch means oppositely and simultaneously, means urging the lastsaid manual means to close the first switch means and open said secondswitch means.
 19. The combination called for in claim 18 in which saidthird electrical connection includes an electrical current flow limitingdevice, and switch means for shorting out said device.